Even the best putters have a tough time every once in a while with the speed of a putt. When you find yourself struggling to get the ball near the hole on a lag putt try the following drill.
Putt with your eyes closed
Begin by setting up for a 6 foot level putt. Setup properly with your eyes open first and then when you are ready to pull the trigger close your eyes and try to feel the appropriate stroke that will put the ball into the hole. To have even more success with this drill keep your eyes closed and try to guess if the ball went passed the hole, short of the hole or just right. If this gets too easy for you back up to a longer distance to practice your lag putting and your “feel.” With time your stroke will become more and more intuitive and your distance control will be just as good as the guys on tour.